...Morning san joaquin valley fog again tuesday......Storm to reach central california wednesday followed by anotherStorm friday into the weekend...

High pressure over california will keep conditions favorable forThe development of late night and morning fog in the central andSouthern san joaquin valley again tuesday. The fog will begin toDevelop around midnight and will become more widespread towardDaybreak. The fog will begin to lift by mid morning and dissipateAround noon.

Driving in dense fog is extremely hazardous as visibilities canBe reduced to below a quarter mile. If it is absolutely necessaryTo drive in foggy conditions...Slow down...Turn your headlights onIn low beam mode and leave extra stopping distance between you and theVehicle in front of you. Drive defensively!

The high pressure will give way mid-day tuesday to an approachingLow pressure system. This storm will affect mainly the northernHalf of the district...With the best chance for rain and mountainSnow from fresno county northward. Snow levels will start outAround 7000 feet near yosemite...Rising to around 8000 feet in theTehachapi mountains. Snow levels will fall by about 500 feet byThe time the storm moves east of the region wednesday night.

A second storm is expected to reach california beginning thursdayNight. This storm is forecast to linger over the state through theWeekend...Bringing periods of rain and mountain snow to the centralCalifornia interior. Snow levels will start out around 7000 feetNear yosemite...But fall to around 6000 feet by sunday evening.Further south...Snow levels will be around 7000 to 7500 feet inSequoia national park...And around 8000 feet in the kern countyMountains.

...Storm to reach central california wednesday followed byAnother storm friday into the weekend...

Last day for patchy dense fog in the san joaquin vally as theUpper ridge of high pressure over california breaks down andClouds will increase later today into tonight. The fog will beginTo lift by mid morning and dissipate around noon.

The high pressure system that has brought us above normalTemperatures over parts of the san joaquin valley will give wayLater today to an approaching low pressure system by wednesday.

The first storm will produce around three quarters to one inch ofRain from fresno county northward into merced county and one halfTo three quarters of an inch of rain from north of kern county toFresno county and less than one quarter of an inch in kern county.Snow levels will be around 7500 feet near yosemite...Rising toAround 8000 feet in the tulare county mountains south to theTehachapi mountains. Snow accumulations above 8000 feet with thisFirst storm will range from 6 inches in sequoia national forest toAround a foot at yosemite national park.

Winds will also be a concern with this system. Strong southerlyFlow ahead of the cold front early wednesday will produce southWinds 25 mph with gusts to 35 mph near merced and sw winds 30 mphWith gusts to 45 mph along the west side of the san joaquin valleyBelow the cottonwood and pacheco passes. Winds may also be strongIn the south valley near the base of the grapevine.

A second storm is expected to reach the northern part of theRegion beginning thursday night. This storm is forecast to lingerMainly north of fresno county through the weekend...BringingPeriods of rain and mountain snow. Rainfall with this system willBe around one quarter to three quarters of an inch north of fresnoCounty with the higher amounts near merced. Rainfall amounts willBe less than one tenth of an inch north of kern county to fresnoCounty and little or no precip is expected in kern county. SnowLevels will range from around 7500 feet near yosemite...To around8000 feet in sequoia national park...And around 8500 feet in theKern county mountains. Snow accumulations above 8000 feet withThe second storm will range from around 6 inches in sequoiaNational forest to around a foot at Yosemite National Park.

.Synopsis... The upper level ridging that brought the patchy denseFog to parts of the san joaquin valley this morning will quicklyExit the region by this afternoon. This will be followed by theApproach of a broad upper level low over the pacific. The presenceOf this storm will increase cloud cover today and increasePrecipitation chances for wednesday through sunday especially in theNorthern parts of the forecast area.

&&

...Updated for ending of dense fog advisory...

.Discussion...

Last remnants of valley fog have dissipated and the dense fogAdvisory has ended. Forecast has been updated for this...OtherwiseNo changes.

&&

.Prev discussion... /issued 424 am pst tue nov 27 2012/

Discussion...Significant pattern change in store for the central ca region asMeridional flow in association with a long wave trough begins toMove eastward and impact the west coast of the us. SpecificallyThe central ca interior will miss the brunt of the amplifiedPattern that is expected by both the european and us models.

Qpf amounts that are "significant" are expected across nrn ca.Qpf amounts quickly taper off as you head into the southern sierraAnd the nrn sjv and into the central ca interior. Extended modelsAre still having some timing differences this run. However, qpfAmounts are similar and we are taking a blend of the 00z euro and00z gfs for timing and intensity.

We are looking at two events right now...With the first one inHere by early wed. Ahead of the front we are expecting strong swWinds along the west side of the sjv and near merced. Once theFront pushes through we will begin to see rain spread over theRegion as the first system is expected to move through by late wedPm. This will be a warm system with its origin from the centralPac and snow levels will remain high through the event...With snowLevels around 7500 feet near ynp to 8500 feet near sequoiaNational park. Snow amounts will be higher near ynp with around aFoot expected for the first event.

There will be a break in the action on thursday before the nextSystem moves in to our north and clobbers the nrn ca region. WeWill just get brushed by the system as it moves inland and theBulk of the precip will be confined to fresno county northward.Merced could see up to three quarters of an inch with the secondSystem and may see some isolated flooding in flood prone areas.Snow will once again be concentrated over the ynp area and willContinue to be around 7500 feet and slowly drop as the systemMoves through by sunday. This will be a prolonged event and willBe confined to the areas north of fresno county. The central andSouthern sjv will see little precip during this event...Except asIt winds up and moves out they will see some precip and gustyWinds on sat.

Fog will not be a concern during the stormy period...But willReturn early next week to the sjv as an upper ridge returns.

&&

.Aviation...Areas of ifr and local lifr visibilities in fog in the san joaquinValley until 18z wed. Than mvfr conditions in haze thru 12z wedOtherwise...Vfr conditions will prevail across the remainder of theCentral ca interior thru 12z wed.

The level of certainty for days 1 and 2 is medium.The level of certainty for days 3 through 7 is medium.

This information is provided as part of a trial project conductedBy the national weather service san joaquin valley - hanford.Certainty levels include low...Medium...And high. Please visitWww.Weather.Gov/hnx/certainty.Php /all lower case/ for additionalInformation and/or to provide feedback.

...No flooding is expected on mainstem rivers at this time due toDry conditions over the past year and ample reservoir storage...

A broad area of low pressure will anchor over the northeast pacificOcean the next several days...Sending a series of wet...Warm stormsInto northeast california...The eastern sierra and western nevada.This will cause periods heavy precipitation beginning wednesday andContinuing through sunday. This will increase the chance for urbanAnd small stream flooding...Along with significant rises on someMainstem rivers this weekend. Heavy rain on burn areas in lassen andDouglas counties...May cause mud and debris flows.

Total precipitation amounts over the next five days...Through sundayMorning...Could be as high as 8 to 10 inches along the sierra crestNorthward to western lassen county...With up to 4 inches in the lakeTahoe basin...And up to an inch on the valley floors along highway395 in western nevada. Snow levels during these storms are expectedTo range between 6500 to above 9000 feet. The period of heaviestRain...Along with snow levels above 9000 feet is expected saturdayAfternoon through sunday morning.

The potential for small steam and urban flooding is high saturdayAfternoon through sunday morning in the following areas...

In eastern california...Extreme eastern modoc county...Lassen county west of highway395...Eastern plumas...Eastern sierra...The lake tahoeBasin...Eastern alpine and mono county west of highway 395.

In western nevada...Areas along and west of highway 395...Which includes the foothillsWest of reno...Carson city...And douglas counties.

Although no mainstem river flooding is forecast at this time...TheSusan river at susanville may rise to within a foot of the 12 footFlood stage by sunday morning.

A flood potential outlook is issued when there is the potential forSignificant rises or flooding along rivers and streams. ThisStatement will be updated by 3 pm wednesday november 28th.

Keep informed of the current situation by monitoring nationalWeather service flood watches...Warnings and statements atHttp://weather.Gov/reno.

No major changes to the forecast today, though confidence isIncreasing in periods of heavy precip for the sierra and highWinds in the lee wednesday-friday. We`ll be issuing a high windWatch for tahoe, reno, mono zones thurs night and friday, but noSnow advisories/watches for the sierra since snow levels areLikely to be too high for major impacts.

First storm is on track to swing through tomorrow with a periodOf hvy precip in the sierra. Negative tilt trof and thin moistureRibbon suggest a quick hit with only a few inches of wet snowAbove 6500 ft. Mslp gradient and increasing flow aloft will resultIn gusty winds area wide as well. Lake wind advisories will bePosted.

Brief lull in systems thursday but it won`t be much of a break wxWise with winds increasing during the day. More substantial windThreat for tahoe and lee side looks to be thurs night and friday,With 700mb flow near 60 kts, precip banking up west side of plumasCounty, and decent mtn wave/downslope signatures showing up evenIn gfs. Sref plume diagrams also indicate period of high winds inLee, so we`ve gone ahead with a watch. This has the potential ofBeing a rather strong wind event late thurs night intoFriday...Definitely worth keeping an eye on.

Good atmospheric river setup with this second storm friday intoEarly saturday will raise snow levels resulting in mainly rain forAreas below 7500 ft. Potentially 2-4" liquid for crest areas northOf tahoe; amounts dropping off rapidly to the south. We`ve issuedA hydro outlook to address potential rises in streams and riversDue to this heavy rain. Spillover chances into western nv are onlyModest with shadowing signals showing up in gfs/ec data but we`veKept high chance pops for reno/carson area due to uncertainty.Snow amounts in sierra could be up to a foot, but it would beAbove 8000-8500 ft for the most part, with only localized impactsTo travel.

The main forecast issues are snow levels and rainfall amounts,Which will dictate runoff at high elevations, and factor into theUrban and small stream flood potential. Latest models runs are inGood agreement in snow levels rising well above 8000 feet. A fewModel runs have shown snow levels for the tahoe basin and monoCounty, may rise to 11,000 feet prior to the frontal passage andDuring the period of heaviest precipitation saturday night andEarly sunday.

We do want to emphasize main-stem river flooding (truckee,Walker, carson and susan rivers) is unlikely at this time due toAmple reservoir storage relatively dry soil conditions. HoweverThose living near rivers, creeks and streams will want to remainAware of the forecasts through the weekend as river levels will beOn the rise.

Rain will intensify the northern sierra saturday, with light rainPushing across into western nevada. The period of highest snowLevels and heaviest rain is focused from saturday night intoSunday afternoon as the front moves through the sierra and westernNevada. Potential is there for 6 or more inches of rain fromWestern lassen county southward to along the sierra crest from theTahoe basin to mono county. Farther east, 2-4 inches are possibleIn the tahoe basin to the foothills just west of highway 395, withUp to an inch on the western nevada valley floors. There are a fewFactors which could produce more rainfall, especially if the frontMoves through the region slowly and warm rain processes increasePrecipitation efficiency as the front interacts with atmosphericRiver.

Once the front passes snow levels should drop to near 5000 feetWell north of i-80, near 6000 feet for reno-tahoe and near 7000Feet south of highway 50. However the event will be ending as theSnow levels drops, so significant snow accumulations may not occurWith this event.

High pressure is forecast to build over the sierra and westernNevada monday and tuesday, with warm and dry conditions. Models doHint at a second warm moisture plume reaching the west coast forThe middle of next week. Brong

&&

.Aviation...

High pressure will bring vfr conditions, light winds and a highClouds through tonight. A fast moving system will bring period of(roughly 6 hours) moderate to heavy rain/snow in the tahoe basinAnd northeast california after 18z wednesday. Across westernNevada rain and gusty winds are possible wednesday afternoon.Conditions should fall to mvfr in rain for the tahoe basin andNorthern sierra terminals. Snow is unlikely to accumulate onRunways below 6500 feet.

Much stronger winds will reach areas south of portola to lovelockThursday night and friday. Surface gusts may exceed 50 kts,Especially at mammoth and perhaps reno-carson-minden. Certainly aHigh potential for mountain waves, turbulent approaches and lowLevel wind shear at all terminals.

A period of heavy rain is likely in the sierra and far westernNevada, with high freezing levels, saturday night into sunday. Brong

This Afternoon: Total daytime snow accumulation of 15 to 21 inches possible.Tonight: New snow accumulation of 6 to 10 inches possible.Thursday: New snow accumulation of 29 to 35 inches possible.Thursday Night: New snow accumulation of 37 to 43 inches possible.Friday: New snow accumulation of 24 to 30 inches possible.Friday Night: New snow accumulation of 16 to 22 inches possible.Saturday: New snow accumulation of 22 to 28 inches possible.Saturday Night and Sunday: more snow.

...Three successive storm systems will impact the central californiaInterior through the weekend...

The first storm will produce up to a half inch of rain from fresnoCounty northward today with local amounts of an inch over theHigher terrain. Rain amounts will be much lighter over the southernSan joaquin valley and along the west side where up to a tenth ofAn inch may fall by this evening. Snow levels will be relativelyHigh...Generally above 8000 feet except near 7500 feet in yosemiteNational park. Above these elevations...This first storm willProduce snow accumulations of 3 to 6 inches with local amounts ofUp to 10 inches by tonight.

A second storm will bring precipitation into merced and mariposaCounty thursday night. Wet weather from this system will stayPrimarily north of kern county friday as the storm moves inland.The heaviest precipitation will fall in the foothills and higherElevations of the sierra from fresno county northward where anInch or more of rain is likely. In the san joaquin valley...ThisSecond storm will bring rain totals ranging from just a fewHundredths in kern county to nearly a half inch in merced county.Snow levels will remain high through friday night with snowAccumulations of 6 to 10 inches above 8000 feet.

Storm number three will arrive saturday night or sunday and bringMore substantial precipitation to the central california interiorIncluding the kern county desert...With the potential for heavySnow accumulations in the southern sierra nevada above 8000 feet.

Two storm systems in the eastern pacific will bring episodes ofRain and gusty winds to much of the central california interiorThursday night and friday...And again sunday.

The next storm will bring precipitation into merced and mariposaCounty late thursday night. Wet weather from this system will stayPrimarily north of kern county friday as the storm moves inland.The heaviest precipitation will fall in the foothills and higherElevations of the sierra from fresno county northward where anInch or more of rain is likely. In the san joaquin valley...ThisSecond storm will bring rain totals ranging from just a fewHundredths in kern county to nearly a half inch in merced county.Snow levels will remain high through sunday with snowAccumulations of 6 to 10 inches above 9000 feet.

Storm number three will arrive saturday night into sunday and bringMore substantial rain...With heavy snow accumulations in theSouthern sierra nevada above 9000 feet. These storms could bringMinor flooding in areas of poor drainage this weekend with thePossibility of mud slides or debris flows in the foothills andHigher elevations of the sierra. Gusty winds are expected in theSan joaquin valley north of fresno county and west of interstate5 thursday night through midday friday...And again on sunday.

Two storm systems in the eastern pacific will bring episodes ofRain and gusty winds to much of the central california interiorToday and again saturday night and sunday.

The next storm will bring precipitation into merced and mariposaCounty early this morning...Spreading south during the day.Heaviest rain and high elevation snow will stay north of kernCounty as the storm moves inland. The heaviest precipitation willFall in the foothills and higher elevations of the sierra fromFresno county north...Where an inch or more of rain is likely. InThe san joaquin valley...This second storm will bring rain totalsRanging from just a few hundredths in kern county to nearly a halfInch in merced county. Snow levels will remain high throughSaturday with snow accumulations of 6 to 10 inches above 9000Feet.

The storm that follows will arrive saturday night into sunday andBring more substantial rain. Heavy snow accumulations are likelyIn the southern sierra nevada above 9000 feet. Rainfall from bothOf these storms could cause street and urban flooding in the sanJoaquin valley from fresno county northward this weekend. In theFoothills and higher elevations of the sierra...Heavy rain couldBring small streams and rivers to bankfull or higher by sundayAfternoon. There is also the threat of rock slides...Debris flowsAnd road closures.

Additionally...Gusty winds will occur in the san joaquin valleyNorth of fresno county and west of interstate 5 today and againOn sunday.

.Synopsis...The next system to move in from the pacific will arrive thisMorning with rain spreading south across the area during the day.Heaviest rain will be from fresno north. A break in thePrecipitation will occur tonight and saturday.

The third...And strongest system will arrive saturday night andSunday. This system has the potential to bring heavy rain at timesTo the san joaquin valley and adjacent foothills...Especially northOf kern county.

&&

.Discussion...The next sys to impact the region was just to the north...From theBay area to tahoe. This sys will gradually side south thru the dayWith precip spreading south across much of the area this morningThen into kern cnty in the mid to late aftn. Fairly potent pvaMovg thru the base of the parent upper low was pushing toward theCentral coast. This will interact with the front later this mrngInto early aftn...And should produce some decent rain from fresnoNorth. The front will weaken later today as upper dynamics shearEast. Rainfall will taper off farther south in kern cnty...ButThink everyone there will get a few hundredths...With psblException of the deserts. Snow levels this mrng ranging from7500-8500 north to south...And will rise about 1k ft as bulk ofPrecip arrives.

The stalled and basically washed out front will linger tonite intoSat. This will keep some residual precip mainly in the mtns intoMid aftn sat. Then the third and possibly the strongest of theCurrent series will be approaching the central ca coast. RainShould begin the the north around mce-ynp late in the afternoon orEarly evening. Rain may remain hung up for a while in the north asThe main shortwave and strongest dynamics push across norcal. RainWill then spread south quickly sun mrng and encompass most all ofCentral ca in the aftn. Strong orographics set up across the srnSierra with this sys...And model qpf ranging from 3-6 inches fromYnp south to kings canyon...Tapering off rapidly to a fewHundredths in kern cnty. Sjv qpf will range from 1-1.5 inches fromFresno north...Tapering off to around 1/2 inch from nlc/hnx/vis toA few hundredths in the south end. Snow levels aoa 8k sun willDrop to around 6500 ft in ynp sun nite. However by then much ofThe precip will already be over.

For mon and into the new week...Models similar in yet another s/wvTrof moving into norcal early tues...Sagging slowly south. CouldSee some sct light precip from fresno cnty north beginning lateTues. The remnant front becomes quasi stnry from mtr bay to ynp.Thus some light showers fresno north into possibly early thurs.Elsewhere dry. Fog chances in the sjv seem to be diminishing someAs the area remains in a weak trof and lots of clouds into midWeek. A pattern chance is suggested late in the week with a highAmp meridional flow developing...With a strong ridge building overThe eastpac/west coast states...And a deepening trof ern u.S. ButThat is beyond the scope of this fcst attm.

&&

.Aviation...Over the san joaquin valley and adjacent foothills...Rain becomingLikely this morning then turning to showers after 00z sat with areasOf mvfr and local ifr thru 12z sat. Over the southern sierraNevada...Rain and higher elevations snow continuing with areas ofIfr conditions in mountain obscurations thru 12z sat. Over the kernCounty mountains areas of mvfr and local ifr in rain and upslopeThru 12z sat. Over the kern county deserts ...Mostly vfr conditionsThrough 12z sat. Strong winds with gusts reaching 35kt possible from15z fri thru 06z sat over merced and madera counties and along theWest side of the san joaquin valley.

The level of certainty for days 1 and 2 is high.The level of certainty for days 3 through 7 is high.

This information is provided as part of a trial project conductedBy the national weather service san joaquin valley - hanford.Certainty levels include low...Medium...And high. Please visitWww.Weather.Gov/hnx/certainty.Php /all lower case/ for additionalInformation and/or to provide feedback.